Angioplasty procedures are accepted to dilatate stenoses or blockages within a human body. Examples of such procedures include percutaneous transluminal coronary angioplasty (PTCA) procedures and urological procedures. The present invention will be described with application to PTCA procedures, although the invention is equally applicable to other PTA procedures. The PTCA procedure employs a percutaneous intrusion into the arterial system and advancement of a dilatation balloon catheter to the location of the stenosis. The dilatation balloon is positioned across the stenosis, and the balloon is inflated through use of an inflation device connected to the catheter and in fluid communication with the balloon through a lumen in the catheter.
Most inflation devices currently in use are hand operated. Inflation devices include a syringe having a chamber in fluid communication with the lumen of the catheter, and a piston within the chamber connected to a plunger operable by the cardiologist to increase the pressure of inflation fluid within the chamber. The pressure applied to the balloon may be as great as 15 atmospheres or more, during a typical PTCA procedure. It is not unusual to inflate the balloon to pressures as high as 200 to 250 pounds per square inch.
A typical PTCA procedure requires use of at least an introducer, a guide catheter, and a balloon catheter. The introducer provides percutaneous intrusion through the skin into the arterial system, the guide catheter provides a guide for delivery of the balloon catheter and other items within the arterial system, and the dilatation balloon catheter is advanced within the guide catheter to the stenosis where the balloon is positioned to dilatate the same. A guidewire is often also used to guide the guide catheter and/or the balloon catheter during their respective advancements. Typically, the components are advanced until each component is at the position desired by the cardiologist, whereupon each component is held in a fixed position relative to the other elements, and relative to the stenosis. With the position of each component fixed, the inflation device is attached to the proximal end of the balloon catheter and pressure is applied thereto. Typically, the procedure requires at least two people, and sometimes more, one to hold the position of the components and another to operate the inflation device. It has not been possible for one person to easily and accurately simultaneously maintain component position and operate the manually-operated inflation device.
Power-assisted inflation apparatus have been proposed, but they have not been entirely satisfactory to cardiologists. As an example, it is important that the components used in the PTCA procedure, including the inflation device, be sterile. Manually-operated inflation devices are reasonably economic that they may be discarded after each procedure rather than sterilized. However, most proposed power-assisted inflation devices would be so costly to manufacture that it would not be economically feasible to discard them after each use. Sterilization of such devices after use would also be expensive. Moreover, the PTCA procedure performed with most proposed power-assisted inflation devices would still require two or more persons, so such proposed power-assisted inflation devices would not meet the needs of the users. Further, many proposed power-assisted inflation devices would not provide accurate control over pressure applied to the dilatation balloon. Consequently, power-assisted inflation devices have not been accepted by the users.
There is a need, therefore, for a power-assisted inflation apparatus which may be operated with one hand so that the cardiologist may use the other hand for other purposes (including maintaining the position of the catheter components), and which is economically returnable to a sterile state after use, and which provides easy, accurate control over pressure within the dilatation balloon.